Microsoft is making available a 1 million dormant Xbox Live gamertags for anyone to pickup. If you haven’t subscribe lately or no longer using Xbox live, you may be losing your gamertag. What does Microsoft actually mean by dormant?
Microsoft has apparently been careful about what “dormant” means. This pile of names has been freed from a pool of Gamertags that were created on the original Xbox console and remained unused since that console’s servers went offline in 2010, meaning they were never used to log onto either newer console or through Microsoft’s Web-browser interface.
If you used it at least once online, you’re safe.
From Ars Technica.